Latitudinal distribution of nitrogen isotopic composition in suspended particulate organic matter in tropical/subtropical seas

Natural nitrogen isotopic composition (δ¹⁵N) of suspended particulate organic matter (POM) and nitrogen fixation rates via ¹⁵N₂ assay were measured in surface waters along 120° E from 30° N to 30° S in the Asian marginal seas (the East/South China Seas and the Sulu/Celebes/Java Seas) and the northeastern Indian Ocean in November–December 2005 and March 2006. The POM δ¹⁵N values ranged from?1.8 to 12.2‰ with an average of 3.6‰ and showed a decreasing trend towards the equator in both hemispheres. In parallel, the measured N₂ fixation rates showed an increase from the subtropical to the tropical seas. This implies that a higher contribution of ¹⁵N-depleted POM was derived from enhanced N₂ fixation. Water temperature and the stability of water column were partly responsible for the observed variations in nitrogen fixation. The large-scale spatial variations in suspended POM δ¹⁵N and N₂ fixation rates suggest that the suspended POM δ¹⁵N may be a potential indicator of nitrogen fixation in surface waters in tropical/subtropical seas.     

登陆我国大陆热带气旋的纬度分布特征

登陆点位置是热带气旋研究的重要课题.为消除因资料单一产生的误差, 本文采用1951-2010年中国、美国、日本三套热带气旋最佳路径资料, 分析了登陆我国大陆热带气旋频数的年际变化规律, 并研究了登陆纬度的分布和变化特征. 本文以总结三套资料一致反映的现象为主, 得到以下一些有意义的结果: 从总体上看, 中国资料集内的登陆频数比其他两套资料平均每年约多1个. 1970年后三套资料的登陆频数基本保持不变, 登陆纬度有较一致的北移, 而1970年前两者在三套资料内的变化不太一致. 从单位纬度登陆频数上看, 登陆数绝大部分集中在北纬30° 以下, 且总体上随纬度增加而减少, 其中北纬21°-23° 登陆数偏多, 北纬20°-21° 和北纬23°-24° 登陆数偏少.     

中国近海悬浮颗粒物海水声波衰减

在对颗粒物声吸收机理分析的基础上,根据已有的南黄海和莱州湾海洋调查数据,对中国近海实际海域悬浮颗粒物海水在声呐工作频段内的声波衰减进行了计算分析。结果表明,在悬浮颗粒物浓度高的海水区域内,悬浮颗粒物粘滞性声吸收所造成的声波衰减与不计及颗粒物存在的海水声吸收相比不可忽略。计算分析同时表明,在声呐工作频段内,颗粒物的散射声吸收可以忽略不计。取可使粘滞衰减为较大值的粒径为5μm的悬浮颗粒物海水进行计算,在低于几十千赫兹的频率范围内,当泥沙类悬浮颗粒物浓度高于0.1kg/m³、有机类悬浮颗粒物浓度高于1kg/m³,颗粒物粘滞衰减系数将大于清澈海水的衰减系数。泥沙类悬浮颗粒物海水浓度高于0.1kg/m³、有机类悬浮颗粒物海水浓度高于1kg/m³,可以作为是否需要计及颗粒物声吸收的比较保守的估计判据,或是作为悬浮颗粒物海水达到声学混浊的估计判据。     

吉林省查干湖水体悬浮颗粒物光谱吸收特性研究

用分光光度计法确定查干湖复杂光学特性水体悬浮颗粒物的光谱特性与吸光幅度,在室内可控实验中利用定量滤膜技术对2009年7月15日和10月12日两期水体采集样品处理获得了以藻类色素颗粒和非色素颗粒(无机沉积物,有机碎屑)两种光活性颗粒物质为主要贡献的总悬浮颗粒物吸收光谱,结果显示7月份总悬浮颗粒物光谱吸收谱形在400～42...     

Design and development of original WSN sensor for suspended particulate matter measurements

This paper comprehensively presents key issues in design of an original optoelectronic measurement device built to assess amount of suspended particulate matter. The paper is introduced with a short explanation of concerns with a suspended particulate matter, what role it has in the air quality and how it affects health of human population. Then, problems of construction of the measurement device supported by a theoretical explanation on the basis of Mie theory are discussed. Subsequently, it is followed by an analysis of the device operation both in laboratory and in real conditions. Results obtained with the presented device are compared with the professional measurement equipment and an expensive, outdoor measurement station. Paper is concluded with observations of differences in spatio-temporal PM change at very close but significantly different city locations.     

The composition and optical absorption coefficient of atmospheric particulate matter

The optical absorption spectra of atmospheric dust as determined by transmission and diffuse reflectance spectroscopic methods is discussed in the 0.4 to 40 um wavelength range. Quantitative measurements are presented which show the imaginary refractive index to be about 0.007i, with little wavelength dependence, in the 0.4 to 1.3 μm spectral interval. The absorption coefficients of individual materials found in atmospheric dust are also given. This work suggests that atmospheric dust may be composed mainly of weakly absorbing particles contaminated with small amounts of very strongly absorbing materials such as free carbon. The implications of this are discussed from the point of view of laser beam attenuation and lidar return signals. Mie theory computations for ruby lidar wavelengths are shown which suggest that for some models of atmospheric dust, the concept of an average imaginary refractive index may be misleading. Thus, it may be necessary to consider the individual complex refractive indices and size distributions of more than one constituent material present in the dust. This implies that anthropogenic contributions to the atmospheric aerosol, such as free carbon and other strong absorbers, may be of greater optical significance than their relative concentrations might indicate.     

海洋悬浮颗粒的光谱模拟:ADA与Mie的比较研究

基于海洋悬浮颗粒的折射率、粒径分布特征,利用异常衍射近似ADA(anomalous diffraction approximation)和米(Mie)散射方法进行衰减、吸收和散射效率的光谱模拟,分析两种方法计算结果相对偏差Δc,Δa,Δb及其影响因素,探讨利用计算速度占优的ADA方法进行海洋悬浮颗粒光谱模拟的可行性,研究发现:Δc,Δa,Δb受颗粒粒径、折射率实部和虚部的共同影响,且影响方式复杂;ADA方法满足计算精度(相对偏差小于5%)要求的最小颗粒半径Rmin随折射率和波长等的变化而变化。考虑到ADA与Mie的计算偏差受到多种因素的影响,而且海洋悬浮颗粒组分复杂多样,建议在进行海洋悬浮颗粒光谱模拟时,采用经典的Mie方法,而不是计算相对快速的ADA方法。     

Impact of diazotrophy on N stable isotope signatures of nitrate and particulate organic nitrogen: case studies in the north-eastern tropical Atlantic Ocean

During two independent cruises in the north-eastern tropical Atlantic Ocean, we applied two different approaches to investigate the impact of diazotrophy on nitrogen stable isotope signatures in nitrate and particulate organic nitrogen (PON) of the food-web constituents. The first approach, used during the Poseidon cruise 348 in the Mauritanian upwelling, investigated the long-term influence of diazotrophy on the natural abundance of δ¹⁵N-NO^? ₃ and PON. The second approach, adopted during the Cape Verde field cruise, applied stable isotope tracer addition experiments. These served to determine the instantaneous transfer of diazotrophic N to the higher trophic level. Both approaches showed that N₂ fixation was compatible with the pattern and the magnitude of the isotopic depletion of dissolved NO^? ₃ during the Mauritanian upwelling cruise, as well as PON in zooplankton and phytoplankton during the Cape Verde cruises. An N-budget using ¹⁵N incorporation rates and diazotrophic N₂ fixation rates showed that 6 % of the daily N₂ fixation was potentially taken up by the mesozooplankton community. Direct grazing accounted for 56 % of gross mesozooplanktonic N incorporation, while 46 % occurred due to channelling through the microbial loop.     

EDXRF analysis of suspended particulate matter (SPM) from residential and industrial areas in Cairo,Egypt

Due to the remarkable increasing of the mass concentrations of suspended particulate matter (SPM) as an air pollution indicator in Greater Cairo‐Egypt, regular sampling during autumn 2014 and winter 2014/2015 seasons has been performed from industrial and residential areas. It was found that the average mass concentrations of the SPM collected from residential and industrial areas are equal to 531 ± 198 and 912 ± 230 μg/m³, respectively. These quantities are much higher than the maximum allowance level, especially for the industrial area. By utilizing three secondary targets, energy dispersive x‐ray fluorescence working under vacuum environment was used for elemental analysis of 19 elements namely; Na, Al, Si, S, Cl, K, Ca, Ti, V, Mn, Fe, Ni, Cu, Zn, Pb, Se, Br, Rb, and Sr. The present optimized selective excitation energy dispersive x‐ray fluorescence analysis has considerably enhanced the analytical range with respect to our previous similar studies, including low Z elements such as Na, Al, S, and Cl and attaining lower detection limits in the range of ng/m³. Remarkable high elemental concentrations were determined for most of the detected elements from the industrial area samples, strongly indicating the influence of the industrial and anthropogenic activities. The average percentages of the mass concentration of the detected inorganic elements account only for 3.2% and 10.5% of the total mass concentration collected from the residential and industrial areas, respectively, thus directly indicating that the content of organic pollutants in SPM is the dominant contribution.     

Spectroscopic determination of the nitrogen isotopic composition in the region of subnatural15N concentrations

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 50, No. 3, pp. 407–412, March, 1989.     

Elemental composition of fine particulate matter (PM2.5) in Skopje,FYR of Macedonia

Aerosol samples were collected at an urban background site in Skopje, Former Yugoslavic Republic of Macedonia, during four measurement campaigns from December 2006 to October 2007. An impactor was used to collect particulate matter (PM_2.5) aerosol particles and the samples were analyzed for the concentrations of particulate mass, black carbon (BC), and 17 elements. The 12‐h average PM_2.5 concentrations varied in the range 10–140 µg m^?3 with the highest concentrations measured during wintertime pollution episodes and during the summer period. Pair‐wise correlations and crustal enrichment were studied and the data set was analyzed by factor analysis and positive matrix factorization. Major aerosol components were identified as mineral dust (main observed tracers Si, K, Ca, Ti, Fe, Sr, and Rb), combustion (BC, S, K, V, and Ni), traffic‐related aerosol (Pb and Zn), and secondary sulfate combined with mineral dust. Combustion sources dominated during wintertime and were likely due to heavy oil combustion, biomass burning, and other industrial activities within the city area. Mineral dust was observed throughout the year, but the concentrations peaked during the unusually hot and dry summer of 2007. It is concluded that Skopje suffers from serious air pollution due to central and residential heating, the transport sector, and industrial activities within the city, and contributions from mineral dust increase the PM_2.5 concentrations under dry periods. Topography and meteorological conditions aggravate the problems and make the air quality comparable with the conditions in other highly polluted cities in Southern Europe and worldwide. Copyright © 2011 John Wiley & Sons, Ltd.     

Removal of organic matter and ammonia nitrogen from landfill leachate by ultrasound

Experiments on the removal of organic matters and ammonia nitrogen from landfill leachate by ultrasound irradiation were carried out. The effects of COD reduction and ammonia removal of power input, initial concentration, initial pH and aeration were studied. It was found that the sonolysis of organic matters proceeds via reaction with ()OH radicals; a thermal reaction also occurs with a small contribution. The rise of COD at some intervals could be explained by the complexity of organic pollutant sonolysis in landfill leachate. Ultrasonic irradiation was shown to be an effective method for the removal of ammonia nitrogen from landfill leachate. After 180 min ultrasound irradiation, up to 96% ammonia nitrogen removal efficiency can be obtained. It was found that the mechanism of ammonia nitrogen removal by ultrasound irradiation is largely that the free ammonia molecules in leachate enter into the cavitation bubbles and transform into nitrogen molecules and hydrogen molecules via pyrolysis under instant high temperature and high pressure in the cavitation bubbles.     

Characterization of iron in airborne particulate matter

In this work soil samples, iron ore and airborne atmospheric particulate matter (PM) in the Metropolitan Region of Belo Horizonte (MRBH), State of Minas Gerais, Brazil, are investigated with the aim of identifying if the sources of the particulate matter are of natural origin, such as, resuspension of particles from soil, or due to anthropogenic origins from mining and processing of iron ore. Samples were characterized by powder X-ray diffraction, X-ray fluorescence and ⁵⁷Fe-Mössbauer spectroscopy. The results showed that soil samples studied are rich in quartz and have low contents of iron mainly iron oxide with low crystallinity. The samples of iron ore and PM have high concentration of iron, predominantly well crystallized hematite. ⁵⁷Fe-Mössbauer spectroscopy confirmed the presence of similar iron oxides in samples of PM and in the samples of iron ore, indicating the anthropogenic origin in the material present in atmosphere of the study area.     

Empirical relationship among wavelength, reflectance, and concentration of suspended particulate matter in water based on a laboratory experiment

A laboratory experiment was designed to collect the spectral reflectance of water containing suspended particulate matter (SPM) in terms of its concentration. By performing surface-fitting analysis, an empirical relationship among the wavelength, reflectance, and concentration of SPM in water was obtained. The results showed that a linear effect of the spectral wavelength on spectral reflectance with increasing concentration of SPM in water, and the relationship between the reflectance and concentration of SPM in water is quadratic. Hyperspectral remote sensing is expected to play an important role in estimating the concentration of SPM in water.     

Chemical and carbon isotopic composition of dissolved organic carbon in a regional confined methanogenic aquifer

This study demonstrates the advantage of a combined use of chemical and isotopic tools to understand the dissolved organic carbon (DOC) cycle in a regional confined methanogenic aquifer. DOC concentration and carbon isotopic data demonstrate that the soil zone is a primary carbon source of groundwater DOC in areas close to recharge zones. An in-situ DOC source linked to organic rich sediments present in the aquifer matrix is controlling the DOC pool in the central part of the groundwater flow system. DOC fractions, 13C-NMR on fulvic acids and 14C data on DOC and CH4 support the hypothesis that the in-situ DOC source is a terrestrial organic matter and discard the Ordovician bedrock as a source of DOC.     

Changes in lithium isotopic composition in hydrogen-enriched Ti/Al systems

Changes in the isotopic composition of electrolyte lithium are studied experimentally when thin-film titanium-aluminum systems are enriched in hydrogen. Strong deviations of the lithium isotope concentration from their natural abundances are observed both in the surface titanium layer and at the titanium-aluminum interface. Analysis of the experimental results permits us to conclude that isotope-induced transformations occur in materials enriched in hydrogen due to cold diffusion of impurity atoms stimulated by hydrogen migration and non-equilibrium chemical reactions. Tomsk Polytechnical University and Fraunhofer Institute for Non-Destructive Testing, Germany. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 29–33, November 1999.     

High‐resolution microanalysis of suspended particulate matter using a transition edge sensor microcalorimeter x‐ray spectrometer

Suspended particulate matter (SPM) collected in the urban area of Tokyo was analyzed using a transition edge sensor (TES) microcalorimeter x‐ray detector mounted on a FE‐SEM system. This prototype microcalorimeter spectrometer with an energy resolution of 19 eV identified some severe peak overlaps in the spectra measured by the traditional Si(Li) solid state detector, including S Kα with Pb Mα, Zn Lα with Na Kα, and Ti Kα with Ba Lα. In addition, the TES microcalorimeter showed good spatial resolution for the microanalysis of SPM. The focused ion beam(FIB) was successfully applied to fabricate a cross section of a single SPM particle. The chemical compositonal difference between surface and inner parts, and among different surface parts of the SPM was also determined. Through combination of the FIB technique and the TES microcalorimeter, we achieved a better understanding of the SPM. Copyright © 2009 John Wiley & Sons, Ltd.